


From Thinnest Air

by TheRechercheRambler



Series: Thin Air [1]
Category: Undertale (Video Game)
Genre: Chapters are only loosely connected early on, Gen, this is unrelated to A Chance Meeting
Language: English
Status: Completed
Published: 2016-01-10
Updated: 2016-02-28
Packaged: 2018-05-13 01:01:22
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 8
Words: 13,835
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/5688520
Author URL: https://archiveofourown.org/users/TheRechercheRambler/pseuds/TheRechercheRambler
Summary: <blockquote class="userstuff">
              <p>Just who was W. D. Gaster? Why is it that we should be wary of him? What's become of him now- and how might he someday come back?</p>
<p>Primarily, this is a story that seeks to portray and occasionally explain the dummied-out content in Undertale from an in-universe perspective.</p>
<p>Latest update, Close Kin: Sans and Gaster have a conversation long overdue.</p>
            </blockquote>





	1. Prologue

“The Underground is a curious place, is it not? Full as it is to the brim with strange people who don't so much as bat an eye at its even stranger magic. But even in such singular surroundings, there are certain things- certain events- whose sheer peculiarity should make them stand out.

And yet, they are almost wholly unknown. To say that they fade or blend into the metaphorical background would be a gross understatement; they may as well be hidden behind the background. People don't give them a second thought, or even a first, for that matter. Recurring apparitions, people who vanished without a trace, and those strange, sourceless devices, somehow garner less attention even than mailed credit card applications.

All of these bizarre things can be traced back to the same single cause; a monster, whose name you might be familiar with. He used to be a most important person down there in the Underground- the Royal Scientist, no less! I don't suppose you're familiar with his accomplishments? Well, let's just say that some scientists have specialties, and this fellow's specialty was everything- from magical engineering, to quantum mechanics, to interspecies metaphysics.

He designed the Core, built it himself- if you can believe the rumors that once flew around here. My, what else? The soul container, the DT Extractor; both devices that sprung from the mind of old Gaster, along with so much more. But, as I said, I _don't_ suppose you're familiar with his accomplishments. Or anything about him, for that matter. No, I don't suppose indeed. You couldn't be familiar with someone who's _gone_. You know as well as I that I don't mean dead.

He's gone, well and truly, not just from the present, but from the past and the future as well. Funny thing about that Core; they say he fell into it, one day. The experience broke him, literally, tore him out of space and therefore out of time. Quite nasty, really. I can't say it's _as if_ he never existed, because, well, he literally never existed. Everything he made, everything he produced, it's all still here, who knows how; it may as well have sprung from thinnest air.”

 

Not everyone forgot about Gaster; at least, not immediately. There were a few whose memories stubbornly refused to change and fade even without any extra aid. A simple-seeming monster, a scientist who worked in the Core, was one such person, and he was most frustrated by the fact that no one else would even acknowledge the existence of his employer and colleague. Now, his plain exterior belied his cleverness, and scarcely a month had passed before he had worked out what had happened to the former Royal Scientist, and less than a month more until he found himself face-to-face with Gaster himself.

Seeing the state that the poor scientist was in, the simple monster decided he had to help him somehow. But try as he might, he could do nothing for Gaster, as such a restoration was beyond his meager power. All it did was cause his magic to be tangled up with the mangled energy that was Gaster's. The simple monster's boldness can be applauded, if nothing else. He followed the vanished man's trail, and scoured the Core searching for him- on that count, at least, he succeeded.

And he never left the Core again.

 

~“Beware the man who speaks in hands,” the river man speaks true,~

 

If you're reading this tale, no doubt you know how intoxicating a good mystery can be, how the speculation and wonder of it all can trap the mind. There was a monster in those days who adored enigmas; and as all of his memories had been erased, his link to Gaster was one of pure curiosity. For, now that all of his knowledge of his acquaintance was gone, he desired to know the origin of the Core, the grand machine of Hotland that powered the entire kingdom. No one he asked could say where it had come from. Some said the Royal Scientist had built it, but beyond that their memories failed them. It may as well have been a feature of the landscape, a natural structure that had existed as long as the Underground itself, for all they knew of it. But this did not deter the knowledge hunter, not in the slightest; it only deepened the allure of the mystery.

Who knows how he hounded out the maze-like machine's secrets, and learned of the history that used to be attached to it. Maybe he found records that had been made resistant to the ravages in time, or perhaps he found it all out by encountering some remnants of Gaster. And encounter he did- several times, in fact, and each time he came away with another fragment of the lost scientist. For he wanted to help him, reassemble him, piece the mystery together- but as he did so, he set in motion his own ruin. He held on too tight, and in doing so ensured that he could never let go. No one ever saw him again.

In fact, no one ever had.

 

~“Let not his mystery ensnare, nor darkness deep cut you,~

 

The fourth unfortunate soul to disappear into thin air was a victim of chance. For she was just a child, living peacefully with her family in Waterfall. She wished to be free of the confines of the Underground, and see the whole world- and in a way, she got it. One day, as she returned home from a walk with her sibling, she heard something, moving about in the shadows. Curious, she strayed away to see what it was, and she saw someone, their shape hidden in the darkness. I'm sure you can guess who it was.

Seeing how downtrodden he looked, she couldn't just pass him by. She went over to talk to him, to see if she could help him, while her sibling went on. It was not long before her family realized she was gone, and went out to look for her by the echo flowers she had been seen by. They looked all over, but never saw her; they didn't know where that child could be. But soon enough they stopped their search- forgot their search, and went back home. Though their memories of her had only begun to fade, they'd forgotten she was missing; the child was gone from reality.

All that was left were echoes.

 

~The thing that goes bump in the night when the time is most late;~

 

Some time had passed, before the final vanishing occurred. This particular monster once knew Gaster personally, although he'd never worked alongside him; he held a high position at a factory in Hotland close by. How he managed to do anything, I can't say, but he was always ahead somehow. Perhaps his memories were likewise ahead of everyone else's, because even long after the scientist was broken this monster could still recall small things about him, bits and pieces. And when he tried to figure out what had happened to his old friend, those were exactly what he found.

Like all the others who followed Gaster, he tried to bring him back. But their souls were not strong enough for such a task, and if they tried to put him back together, to anchor his being to one point in time and space, they inevitably failed. In time, the nature of his existence would overpower them, and they were ripped away from reality with the shattered and scattered scientist. But I needn't say more. You know the rest of their story.

Besides, you never know who might be listening.

 

~If you dare trace the path he trod, you will join in his fate.”

**Notes for the Chapter:**

> I was going to write "river person" in the first line of the poem, and only changed it to "man" to make sure the syllable count/meter worked out, not for any other reason.
> 
> This fic will be updated every Sunday.


	2. Close Call

**Summary for the Chapter:**

> In the forests of Snowdin, Papyrus has a run-in with a monster whose very existence is an enigma.

It was mid-what-passed-for-day-Underground, and out in the forests beyond Snowdin, Papyrus was on patrol for humans. He'd never encountered a human while on patrol before- actually, he'd never seen a human, period, most monsters he knew hadn't- but he knew for certain that several had appeared in the Underground over the years, so this did not deter him in the slightest. Someday, preferably soon, another human would show up while he was in Snowdin, and he, the Great Papyrus, would capture it.

His patrol on that what-passed-for-day-Underground had been proceeding as they always did; recalibrating his puzzles, seeing a few of the other monsters that made Snowdin their home, and not seeing any humans. Most people desperate to catch a human would have found such unrelenting normalcy frustrating; but Papyrus did not, for two reasons. Firstly, he was Papyrus, and he figured that a human was going to come by eventually, and also, said normalcy was soon disrupted.

For while he was out patrolling the forests, Papyrus heard a curious shuffling sound coming from the trees, accompanied intermittently by small noises that in the balance of probability were vocalizations of some sort. This was somewhat suspicious, because Papyrus had already seen the majority of the monsters that lived in the area, except, thankfully, for Jerry, and Jerry sounded much more vile.

Could it be a human at long, long last?!

“WHO GOES THERE?” the tall skeleton called out, barely containing his excitement in his effort to sound like a bold Royal Guardsman, and also not too intimidating (in case the source of the noise was just someone who was in Snowdin for a holiday).

He received no coherent response; just more bizarre noises, which neither grew louder as if in approach nor muffled as if in retreat. If it was a human, then it was doing a terrible job of hiding from him, and if it was someone enjoying their vacation, then why weren't they letting him know? Something was very puzzling with this picture.

“SHOW YOURSELF!” he requested.

Once more, the baffling sounds continued unabated. They were ignoring him! How rude. Papyrus strode forth into the trees to see if he could find the source. In spite of the denseness and dimness of the forest, it did not take much doing to locate it, for not too far from the edge of the conifers, half-hidden in the shadows, was one of the weirdest monsters Papyrus had ever seen.

The monster- well, no; he was more of a pile, an assortment, than he was a monster. Grains and shards and fragments would flake and snap off of him, flying away and dissipating into nothingness, as other bits and pieces appeared from thinnest air to glom onto him, so that all the while he was continuously shifting and reshaping. It was as if someone had tried to sculpt a skeleton out of melting clay, and had not been altogether successful in the attempt, for he looked as if he had been shattered, and then mashed back together.

He was gazing downwards, his expression wistful (as far as Papyrus could tell). His features were unnervingly indistinct and undulating, giving them a somewhat goopy look; the wavy outlines of partly-closed eyes and a mouth that was _probably_ smiling could be made out. A dark line ran from the top of his crescent-shaped right socket up over his head, and another one trickled from below his left socket down by the side of his mouth. Yet somehow, the most unsettling thing about the bizarre monster was how achingly familiar he felt.

Neither skeleton did or said anything for a moment; Papyrus could not help but stare at the malformed monster before him, who seemed to be unaware of Papyrus's presence and continued to gaze at nothing in particular. Then, the conglomeration of a monster looked up.

His eyes widened every so slightly when they met Papyrus's, and a white pupil lit up in his left socket.

“H-HELLO?” Papyrus offered. “ARE YOU FEELING WELL? YOU'RE NOT REALLY LOOKING WELL…”

He trailed off. The other monster gave no reply, but continued to look shocked.

“…WHAT WITH YOU CONSTANTLY BREAKING INTO PIECES AND PULLING YOURSELF BACK TOGETHER.” Papyrus added, for clarification's sake.

As he spoke, a sliver of the goopy monster broke away, and happened to drift near him. Papyrus reached for it, thinking that the strange skeleton would want it back. Before he could touch it, the other monster suddenly gave a cry, which made Papyrus think of a dial-up tone shrieking in an impression of a small child seeing a spider for the first time.

He raised peculiarly disembodied, round hands, with large holes in their palms, and rushed at Papyrus, face distorting in a terrified expression. Then he shoved the tall skeleton back from the sliver, which evaporated away. To further drive home his point, the shifting monster drew himself up to his full height, until Papyrus was looking up at him.

“OKAY! I WON'T TOUCH IT (YOU?)! SORRY!” Papyrus said, raising his own hands up placatingly.

This was apparently enough to calm the shifting skeleton, as he backed away slowly, and settled down in a melancholy heap. The light in his eye flickered out.

Then, he spoke.

He used a language Papyrus was unfamiliar with, some old recherché dialect no doubt, gesturing with his hands as he spoke. His voice was very deep, and just as distorted as everything else about him was. Papyrus got the impression that the other skeleton was trying to explain something to him, although he could not tell what. The sense of familiarity persisted.

When the explanation was ended, the uncanny monster suddenly began to fade away before Papyrus's own sockets.

“WAIT- WHAT ARE YOU DOING? WHO ARE YOU?” Papyrus asked. Before the stranger vanished completely, he started to say something, but Papyrus couldn't tell if he had been able to finish it.

Papyrus was left alone in the forest, with a question running through his head- what was a “Gaster”? The other monster hadn't made any noises that even vaguely resembled “Gaster”, so what was the word doing in his mind? He would have to investigate it later; maybe he'd try calling this “Gaster” person, if they were a person.

This question continued to run a marathon through his head all the way back to his home in Snowdin Village, and along the way it was joined by a few other questions about the apparition in the woods. He had patrolled the area pretty thoroughly that day, so he felt it would be all right if he took a moment to clear his cranium.

There was a photograph in his room, an old one, that he found he very much wanted to look at, although he did not understand why. Nothing about the encounter seemed connected to the picture at all. But, Papyrus supposed as he ascended the stairs, nothing about that meeting had made any sense, so it made sense that this didn't either.

It was of him and Sans, back when they were children. Sans was twelve and Papyrus was nine, but they were the same height (for Papyrus had just started his growth spurt at the time), and they stood side by side. Papyrus was waving happily at the camera, and Sans was smiling lazily.They'd grown up in a happy town, Papyrus recalled vaguely as he looked at the picture, near by the meat factory (for carnivorous monsters). He didn't recall the place too clearly, but he remembered playing with Sans, goofing off, doing usual kid stuff. Strangely, he although it all seemed foggy now, he could still almost hear the nerve-wracking trouble dingle going off, oh- _so_ -loudly. Papyrus frowned. Had that been from the factory, or someplace else…?

There was an awful lot of empty space in the upper half of the photograph.

**Notes for the Chapter:**

> Chapter 3, Close By, will be posted next Sunday.


	3. Close By

**Summary for the Chapter:**

> As they explore the Underground, Frisk stumbles upon people and places which defy all sense by simply being.

Frisk had witnessed lots of weird, out-there things Underground, but a few things really stood out as really inexplicable. Weirder than a ghost making a hat out of tears, or dog residue, or stoves that only turned one way, or melted monsters merged together, or Temmies, or a hotel that didn't leave mints on its pillows. Even Omega Flowey, as they'd taken to thinking of the abomination they'd faced before resetting to befriend Alphys, had an explanation, in the form of the six human souls.

The stuff in Sans's workshop was pretty weird, too, Frisk supposed, but at least that was solidly linked to someone familiar. This _other_ stuff, now… Frisk wasn't sure what to make of it.

 

About half of the things in the extra weird category had occurred in Waterfall. The first one had been just before Undyne had started chasing them; Frisk had been walking around, reading about monster history, and then found themself on a small dock. They'd never been there before, but somehow, they got the impression that it was supposed to be empty.

It wasn't. A scaly monster child in a checkered shirt was standing there, peering out into the inky blackness. She reminded Frisk of Kid, but she was entirely gray- even her shirt!, and when Frisk approached her to say hello and she turned around, her eyes were empty. The monster child smiled cheerfully, and spoke in a soft voice, but her jarring words- Frisk shuddered. A world where you didn't exist, but nothing was different? Frisk had never personally seen _It's A Wonderful Life_ , but they had heard of it, and they felt quite sure that that was not how that sort of story was supposed to go.

They hadn't known how to reply to that at the time, but a bit later, before they went on to Hotland, they'd come back. Frisk still had an umbrella with them, and the sight of it seemed to bemuse the monster child. She'd asked them to forget about her, but how could anyone forget that? After the barrier had been broken, and Frisk had gone back through the Underground, they'd gone back to the dock to see how she was, but she was gone. It made sense, Frisk supposed. After all, surely she had a home, or had left to go to the Surface, but…

Kid didn't know her, apparently. Frisk had asked him if he knew any gray kids that looked a bit like him. He'd seemed thoughtful for a moment, concentrating as if trying to think of a dim memory, but then he'd shrugged (somehow) and said no, he didn't.

 

Not much later after meeting the poor goner kid, another weird thing had happened. They couldn't remember how they'd gotten to that part of Waterfall, but when asked about it monsters tended to smile and nod, oh yes, of course, they knew about the bug-catching place! It wasn't quite so much the place itself as the people that had made the situation weird.

There had been another monster there, in the grass so high it rose up above Frisk's head; a monster, and her bug, and… someone else. Things had only become bizarre when the bug-catcher had asked Frisk if they could _please_ do something about their “friend”. Apparently, this friend's smile was creeping them out something awful. At first, Frisk had thought it was Flowey, and for a heart-pounding moment they'd fretfully scanned the grass for a sign of the wicked weed, sure that he'd just melt in with the other plants. But then they'd caught sight of something else in their peripheral vision.

It wasn't Flowey, but it was smiling, and it did disappear entirely when Frisk tried to get a good look at it. The bug-catcher reacted to that, so Frisk hadn't imagined the half-seen thing, skulking out somewhere behind them.

Oftentimes, events seem strange because they are distinctly singular. They start surprisingly and end abruptly, and seem disconnected from everything around them. But this specter was made all the odder because Frisk saw them again later.

 

Then there was that thing by Napstablook's house. That was still baffling. Frisk had mentioned it to Napstablook, but they had been completely mystified. Whatever it was that had been lurking in their snail stable, they hadn't been aware of it.

On that occasion, Frisk had wandered behind the snail racing track, and found their way to a small clearing with a penned-in area by a snable. It had felt unfamiliar, even moreso than everything else they'd seen in the Underground; although they had obviously never been to the Underground before, this was one of those places that seemed even more new than the rest. They'd been poking around, out of curiosity, and happened to come across a discarded key when they visited the trash can.

Frisk was pretty sure that the moment they fished the key out from the junk it was half-buried in was when the whatever-it-was decided to show up in the snable. Its appearance was indeterminable; Frisk could see little of it besides a tall pale shape that was more of a silhouette than a person. When they approached it, it made a few strange voice-like sounds, but did no more. Thoroughly unnerved, Frisk backed away slowly, heading away from the snable and back toward the track, finally turning and hurrying from the clearing when the freakish thing was out of sight.

They'd asked Napstablook if they knew anything about the weird shape in their snail stable. The ghost had seemed just as confused as Frisk was, and barely seemed to understand what they were asking.

 

The last unusual event that Frisk stumbled upon in Waterfall was perhaps the most inexplicable of all. Much like with the bug-catching place, Frisk did not know how they had gotten to that dark place; it seemed as if they had fallen deep in thought while walking around, and their feet took advantage of Frisk's distraction to take them somewhere new of their own accord.

Perhaps the room had simply been a cave of some kind, devoid of the usual bioluminescent plants that characterized Waterfall. That might explain why it was so prodigiously dark. But then why hadn't there been light filtering in from the entrance? For that matter, where _was_ the entrance? Frisk had never found it again, though they'd searched.

Once they'd become aware that they'd wandered into pitch darkness- how had that happened?- Frisk naturally began immediately to seek for the way back out. As they'd fumbled about, something had appeared in front of them. It looked like the _thing_ that had appeared uninvited in Napstablook's snable; a tall, blank silhouette (of what Frisk hadn't the vaguest clue). When got close to it, the thing became more solid-looking, and when they backed away, it faded and became more transparent.

They tried to speak to it, even. It had spouted some unintelligible simulacrum of words, but did no more. It didn't even move. All it did was fade in and out as Frisk walked around it. Somehow, Frisk got an impression that whatever it had tried to say had been… removed or erased. Finally, they went back to looking for a way out; eventually they found themself back in the familiar lit fields of Waterfall, without any idea of how they'd gotten back or where the bizarre room had been. One minute, they'd been stumbling about blindly, and the next, they were in a place that made sense.

More sense, anyway.


	4. Close Encounter

**Summary for the Chapter:**

> As their journey through the Underground progresses, Frisk encounters beings stranger than any they met before, and is thrust at the heart of a mystery steeped in shadows.

As Frisk traversed Hotland, they were filled not only with determination, but with a strange sense of apprehension that intensified when they got closer to the Core. There was something more than just the magic of monsters lurking there.

Although after everything they had seen in Waterfall, they had hoped that they could take whatever weirdness yet to come in stride, they were still overcome by the thick suspense in the air when they exited an elevator and saw a totally gray monster standing a ways off. This monster did not seem aware of them, even as they approached. He stood ramrod straight, arms stiff at his side, staring off at something Frisk could not see.

Frisk walked up to him, slowing as they got closer. They gulped.

“Hello.” they said politely.

“It makes sense why Asgore took so long to hire a new Royal Scientist.” the monster said tonelessly, as if to himself. Frisk didn't know what he was talking about. Did it have something to do with Alphys?

“After all, the old one… Dr. Gaster. What an act to follow!” he continued, still staring straight ahead. He never even blinked. “They say he created the Core. However, his life… was cut short. One day, he fell into his creation, and…”

His mouth snapped shut, and the room was filled with a heavy silence for a minute.

“And?” Frisk asked tentatively.

“Will Alphys end up the same way?” the monster wondered quietly.

They met an even eerier gray person a little while later, a long-armed monster with only a too-wide smile visible in the darkness of his face. In one outstretched hand, he clutched a pale blob which seemed unable to remain in one shape. Frisk thought it looked something like a head.

“H-hi.” Frisk said, looking up at the monster's face. They weren't consciously afraid of him, the last two gray people they had met had barely even moved, let alone tried to hurt them, but there was something _wrong_ with these monsters.

“Alphys might work faster.” he said, in a surprisingly deep voice. His mouth didn't move as he spoke, but remained frozen in a grin. “But the old Royal Scientist, Doctor W. D. Gaster?”

“I-I've heard of him.” Frisk said. “What did he-”

“One day, he vanished without a trace.” the monster continued. For all the reaction they got, Frisk may as well have never spoken at all. “They say he shattered across time and space. Ha ha… How can I say so without fear?”

Something about the monster's unmoving face unnerved Frisk; they glanced away from it briefly, and saw that he was not the one speaking. The head-like thing in his hand was speaking for him!  
“I'm holding a piece of him right here.”

Frisk stared at the thing the monster was holding with wide eyes, before slowly taking a few steps backwards. As they watched, the monster's body flickered like the screen of an old-fashioned television, and disappeared before their eyes with a high-pitched echoing tone. They fished their phone out of their pocket to call Papyrus and Undyne, and ask them about the weird monster, but once their friends picked up they found they didn't know what to say.

Seconds stretched into minutes stretched into an hour, and as Frisk progressed through the sweltering caverns, they tried to put the curious encounters out of their mind for a while. Before too long, however, they found the third gray monster of Hotland. When they stepped out of another elevator their senses were awash with the feeling of being watched, and suddenly came face-to-face with a colossal, motionless head.

Its neck sprouted out from the ground, without any sign of a body it might be attached to. The thing's mouth seemed unnaturally wide, in Frisk's opinion, even by monster standards. Frisk hesitated a moment, wondering if they should go back and take the elevator again, before taking a deep breath and walking up to the monster.

“Hello.” they said resolutely. The other gray people had been weird, yes, but that was no reason to be impolite.

“I understand why Asgore waited so long to hire a new Royal Scientist.” the head told them. Of all of the strange gray monsters Frisk had met in Hotland, somehow, this one seemed to be the most aware of them.

“The previous one… Dr. Gaster.”

The head swayed from side to side slowly; Frisk supposed it was shaking itself, the way other monsters might shake their heads when amazed.

“His brilliance was irreplaceable.” the head continued. “However, his life… was cut short. One day, his experiments went wrong, and…”

Suddenly, the head stopped talking, and lapsed back into its previous stationary state.

“…He was shattered, wasn't he?” Frisk said, thinking back to what the second gray person had told them.

“Well, I needn't gossip.” the head replied. “After all, it's rude to talk about someone who's listening.”

The sense of apprehension grew even stronger, and although Frisk didn't see any more gray people or apparitions as they went through the Core, they found themselves always looking back over their shoulder, unable to shake the feeling of being watched.

 

Down in the murk and gloom in the True Labs, Frisk had a few other close encounters, almost as harrowing as the Amalgamates and even more determined to refuse explanation. Things that inexorably brought to mind the sort of specters and bogeys that young children know lurk under beds and in dark closets. Beings that kept poor Frisk on their toes, startling at the slightest creak, whirling around from the feeling of being watched, peering around corners because they were afraid to even walk into a possible danger.

They remembered, looking back on it, how fearful they'd been of going any further after seeing the three Memoryheads. Once they'd reached the large room full of beds, they'd hesitated, then climbed into an empty bed and curled up. After a few moments lying there, steeling themselves, they realized they weren't alone. Something tall and lanky was looming over them. Frisk went very still, as most scared children do if they want to avoid the attention of the things that go bump in the night.

But this thing hadn't made a sound, and it hadn't harmed them. For a moment it just stood there, watching, before reaching out to grab them!- but no, it was only pulling up the sheets. Slowly, it tucked Frisk in, then gently patted their head and disappeared. Frisk practically leapt out of the bed after that, although they weren't as afraid of progressing onwards anymore.

Even with that small boost of bravery, though, the second apparition of the True Labs was still extremely unsettling. They still wondered, sometimes, what it was that writhed about and cast shadows on the shower curtains. It wasn't one of the Determination-wrought amalgamations, they knew that much. When they finally plucked up the courage to confront it, and yanked the curtain away, nobody was there.

Shortly after, Frisk first laid eyes on the ghastly DT Extractor. Jumpy as they were, it seemed to them that somehow, it was leering back at them with huge and void-like eyes. Its skeletal crimson shape reminded them of Flowey's abominable other form far too much for their liking. The fact that they had to fight poor Lemon Bread right then and there didn't help reduce that fear of the things in that room one bit. But then, something truly bizarre occurred.

There was a screen on the wall, beyond the DT Extractor. They assumed it would show them Alphys's seventeenth entry, but instead, it simply said “DT EXTRACTION MACHINE  STATUS: INACTIVE”. After reading that, Frisk frowned at the sign for a baffled moment. Then, they shrugged and decided to leave the disturbing room behind- when the sign changed.

Deep in the electrical and computer systems of the Labs, something must have malfunctioned, as the sign glitched most horribly. Its visual readout became entirely corrupted, showing strings of symbols that Frisk didn't recognize, and an audio file was activated, playing a deep voice, words garbled beyond recognition, and besides that indistinct shrieking.

Yet they understood it. Against all sense and logic, the unfamiliar signs conveyed meaning. I would be very much surprised, my good reader, if you have not read the message yourself; for Frisk had at last found the seventeenth entry- just not the one they had expected.

They stumbled upon- or rather, into- a third apparition in the refrigerated room. With all the mist and haze they couldn't see anything clearly, but it felt like a person when they bumped into it. That startled them, but the thing didn't react at all, so they let it be until they got the fans working right. But the only other things in the room were the fridges.

 

They didn't thought much more about the mysteries or Gaster for a while after that. After all, they had enough to worry about, what with their impending fight with Asgore (and then an actual fight with poor Asriel). But as Frisk traveled back through the Underground after the barrier was broken, events conspired to bring him back to the forefront of their mind.

It happened in Waterfall. Now, my good reader, you have probably made some guess already as to where _this_ part of the tale is headed; and if your suspicions concerned a certain gray door, then you were entirely correct. For Frisk had just gone past Sans's telescope when they became aware that the hall they were walking down had not been there the last time they had passed that way.

Frisk backtracked a ways, to see if somehow they had taken a wrong turn somewhere, but when they got back to Sans's telescope they could see that there was no other way heading out of Waterfall in that room. Somehow, a brand-new hallway had decided to take up existence right in the middle of Frisk's route. In Frisk's opinion, this was most inconsiderate.

Well, there was clearly nothing else for it; they had to take the hallway if they wanted to go back through Waterfall, and they were certainly determined to do that. Perhaps they could ask Undyne about it later. Frisk summoned up their courage and resolutely ventured back into the unfamiliar room.

The hallway was not the only new room that decided to start existing at that moment, Frisk saw. For a little ways down it was a tall door, colored entirely gray. For a moment the color gray wandered about Frisk's mind, questing for something it could connect with; it was significant, Frisk was sure- of course!

The sad child, and the disappearing monsters in the Core- they, too, had been this particular hue of gray. A shiver of anticipation scurried down Frisk's spine as they looked up at the peculiar door.

Then, they reached out and slowly pulled the door opened. It swung out without a sound or a gush of air. Frisk cautiously passed through it, and walked down the short gray corridor on the other side, which opened to a wider room. The only colorful thing in that room was Frisk themself; the walls were gray, and the other occupant, who looked as if he had been partially melted, was entirely monochrome.

He seemed to stare through Frisk, who paused on the threshold of the room when they caught sight of him. It soon became clear that he was paying them no mind, so they walked a little closer- and tripped. Frisk was sure that they were going to collide with him, they were so close together, but instead of hitting the mystery man they kept falling and landed face-first on the floor.

Although they were stunned, they scrabbled away as quickly as possible (it is awkward enough to pass through someone, without making things worse by staying there). But still, the white-and-black monster gave took no heed. It was almost as if he wasn't even really there. Then again, he was hardly the first intangible person Frisk had ever met. Could he be a ghost? A hologram? A hallucination? Hopefully not that.

While Frisk was pondering what the monochrome mystery man might be, they noticed that part of the reason that he looked so molten was that small shreds of him were infrequently sloughing off and melting away. He reminded Frisk of a lava lamp. They knew it was rude to stare, but they couldn't help it, fascinated as they were by the odd monster (as young children are wont to be of weird things). As they watched, one of the goopy chunks happened to float close to them.

In the time-honored tradition of the curious, Frisk poked at it. To their surprise, they didn't pass through it; it felt as corporeal as they did, although its texture and consistency was beyond their ability to describe. A trace of fear laced its way through Frisk's mind; was something happening to them? Were they turning intangible, too? Was that why they could now interact with this piece of the monster? Frantically, they reached out a hand and nervously tried to touch what was probably the mystery man's shoulder. Their hand went through him.

The chunk they had poked was still drifting in front of them, albeit growing a little smaller. Frisk cautiously closed their left hand around it, and found that it ceased to shrink when they held it. If the mystery man was intangible, why wasn't this fragment of him? _How can a person be in a room, but also_ not-be _in that_ _same_ _room,_ _at the same time_ _?_ _How can you_ not-be _in a room in the first place_ _?_ Frisk wondered. They thought back to the gray people in Hotland- perhaps…

“Dr. Gaster?” they asked quietly. Hopefully he would just want to talk, and not fight, if he noticed them at all; Frisk was getting a little tired of getting to know people through battle. _It's time to say good-bye_ , they thought.

That got a reaction. The mystery man moved at last, turning his head down to peer at them; when he locked eyes with Frisk, his sockets flew open in utter surprise. He gave a curious warbling cry and melted away completely, leaving them alone in a room with a distinct impression that it wasn't supposed to exist.

Frisk brought up their left hand, and uncurled their fingers. The dark sliver of Gaster was still resting on their palm.

A few months later, on the surface, they tried bringing up Gaster, to see if they could learn more about him. When they asked Mom, her eyes widened in recognition at the name, and she opened her mouth to explain; but then her brows furrowed as confusion set in, and although she assured Frisk that the knowledge was on the tip of her tongue, Frisk got the feeling that she'd never be able to tell them. Asking Asgore went about the same way, familiarity followed by forgetfulness. Alphys actually seemed excited, at first, when Frisk mentioned the name, but she, too, was unable to explain anything.

Undyne hadn't been familiar with the name at all. Frisk had asked her out of the blue one day, while they were hanging out; Undyne had been playing a simple tune on the piano, and for whatever reason, the memory of the encounter had come back to them. It made sense that she hadn't been able to clear things up, Frisk supposed; she wasn't much for science, except for what she learned through Alphys. When she'd been asked, though, Frisk had gotten the sense that they were being watched, of eyes practically boring into them. The only other person in the room had been Sans, and he'd been looking at something in the opposite direction. He acted as chill as usual afterwards, but he seemed on-edge.

Frisk hadn't asked him, or Papyrus.

**Notes for the Chapter:**

> I couldn't resist referencing Rosencrantz and Guildenstern Are Dead.  
> "I've often not been in rooms."  
> "No, what you've been is not in rooms."  
> Chapter 5, Close Enough, will be here next Sunday, and it is at that point that the story will develop something actually resembling a plot.


	5. Close Enough

**Summary for the Chapter:**

> The fun didn't stop when the barrier was broken. A full year later, Papyrus and Frisk find themselves in the midst of another mystery.

It was what-passed-for-night Underground but, as usual, Papyrus was wide awake. The barrier had been broken well over a year ago, and monsterkind was taking to life in the sun like Onion-san to water, but there was still a lot of work to be done before they could be considered well and truly settled. Alphys was staying in Hotland for a while, to sort out what in the Labs still needed to be taken to the surface. Undyne, of course, had gone with her, so Papyrus had decided he wanted to go and make it into a proper trip, and therefore Sans was going to at least make guest appearances. With so many of their friends all going on a brief vacation Frisk wanted in, which meant Toriel was chaperoning everyone. For the time being, they were housing in New Home, since Undyne and Papyrus didn't want to be in Hotland the whole duration of the trip.

Oh, and the Memoryheads came too. Although Alphys had tearfully sworn that she remembered keeping very thorough records of her patients, one had been able to figure out who they had once been, or who their families were. They weren't telling- all they could really do was babble, to everyone's consternation, including their own- but they seemed to be fine staying with Alphys until something else could be worked out.

But it was not because of work, or because of sleepover shenanigans, or because the Memoryheads were attempting to talk to him, that Papyrus was awake (although there _had_ been plenty of all that). Nor was it simply because he didn't often sleep; after several days, even he began to feel somewhat less energetic. On that particular time-that-passed-for-night-Underground, Papyrus was wide awake because he couldn't turn his brain off. I'm sure you, my good reader, are at least somewhat familiar with the feeling.

He felt quite certain that he had forgotten something important, but could not for the life of him figure out what it was. They had been in the Underground for three days, and the whole time he had been blissfully unaware of having forgotten anything, until quite suddenly, on the third time-that-passed-for-night, the skeleton was hit very hard with the bonetrousling sensation that he really ought to recall… something.

Papyrus was pretty sure he remembered turning off the lights in the house and locking the door when they left, so that wasn't it. Had he had an impending appointment? Like a trip to the dentist's? Well, if he had, there was nothing he could do about it now. Besides, that didn't seem urgent or pressing enough to account for the enormity of bother this forgotten _thing_ was causing him. Whatever it was, he was inexplicably certain that it was a thing of especial consequence. In fact, the more he wracked his brain about it, the more significant it seemed. In fact, it was beginning to seem so huge, so massively important, that Papyrus was beginning to wonder just how he could have lost track of it in the first place. That didn't seem like him.

Maybe Sans would know? That was also of little help, because Sans was napping and would refuse to wake up for several more hours. Papyrus let out an exasperated sigh. Without no better ideas forthcoming, the skeleton decided that the only thing for it was to go back to the Core and Labs in Hotland. Perhaps if he retraced his steps from that day he might hit on something, like how going back to a room after one has left it and forgotten why they did so in the first place can be illuminating.

Papyrus left the room and made to leave the house in New Home they'd appropriated, first retrieving his phone from the nightstand and tucking it under his scarf, beside the old photograph. He still wondered about it, every now and then, and what about the meeting with the mystery monster had made him think about that particular picture. There was nothing overt about it that seemed to warrant such curiosity that Papyrus could see, except for the unusually large amount of blank space, but that just made it all the more intriguing.

It was still beyond belief in the old capitol, Alphys's friends and a growing warren of dust bunnies the only inhabitants. The creak of the front door as Papyrus opened and closed it could, under those circumstances, have wakened the dead- or, more impressively, Sans. Papyrus's footsteps made a similar racket, as he started off on his way toward Hotland; and so did something else.

In the vast, desolate cavern, the distant and dim noises were as loud as if the source had been standing at Papyrus's side. They were the sounds of slow, shambling movement, and the only things the skeleton could think of that might be making them were the Memoryheads. What might amalgamates be up to at that hour?, he wondered. Perhaps they were also having trouble sleeping?

The skeleton continued on through the empty city streets, the shuffling of the Memoryheads and his own footsteps breaking the silence, the latter echoing faintly in the darkness. As he walked, Papyrus began to hear another set of quiet steps, coming up a street near him. He paused, and turned to see if he might spot which of his friends had decided to go out on their own night-time stroll. For a moment, he saw no one, but he realized that the echoes of his own steps were not fading away as one might expect. They had seemed perfectly synchronized with him as he'd walked, but once he'd stopped the echoes had simply gone on without him. Just how many people were up at this hour?

“HELLO?” Papyrus called out, glancing about the boulevard, and the other small street that cut across it. Judging by the volume, the source of the sounds had to be close by. The echoes abruptly came to a halt, although the other set of steps did not.

As he peered into the shadows, out of the corner of his socket he thought he saw someone standing away over on the smaller street. They were too lanky to be Toriel, too tall to be Sans or Frisk, and didn't have red hair, ruling out Undyne. When he turned his head to get a better look at them, they were gone.

“Papyrus?” Frisk's voice said. The skeleton looked back down the boulevard, and saw the small human approaching, one hand stuffed in their pocket.

“AH! HI, FRISK!” Papyrus said. “SO YOU COULDN'T SLEEP, EITHER?”

Frisk shook their head. “Where are you going?” they asked.

“HOTLAND!” Papyrus said. When Frisk looked surprised- from what they knew, Papyrus loathed Hotland, if only for its over-reliance on vents and conveyor belts- the skeleton explained his hypothesis of how it would help him remember… something.

The two went on together. Once or twice more Papyrus thought he glimpsed the shadowy stranger, but he put it down to a trick of the light- er, shadows- or perhaps his own tiredness. It didn't feel like too much time had passed before they had gotten to the elevator that lead down to the Core in Hotland. The doors opened to admit them almost silently.

Papyrus hit the button that would open the elevator at MTT Resort, he was quite certain, but when the doors slid open again the two of them found they were looking out at the Core. Alphys hadn't said anything about rerouting the elevator that day; something wasn't right. Neither of them left the elevator, and the skeleton re-pressed the MTT button, then tapped the close door button. Nothing happened. He tapped it a few more times, but nothing continued to happen. The elevator refused to close, and from somewhere below them came the sound of something knocking on metal, which reverberated throughout the elevator shaft.

They got out after that. It was very dim down there; the bare minimum amount of lights needed to at least see the silhouette of one's hand were lit. Papyrus had to admit that it looked a tad spooky, but Frisk was there with him, so the small human probably wouldn't be too frightened by it. Besides, Alphys was also in there somewhere.

“WELL. I STILL CAN'T REMEMBER.” Papyrus announced. “I GUESS WE'LL JUST HAVE TO KEEP GOING!”

Frisk shrugged, but didn't protest, and followed after their friend. As they walked through the network of twisty little passages, all alike, the human felt, somehow, that they were not alone. The air was perfectly still, but tense, as if the building itself was anticipating something. They could feel a watchful awareness in the walls around them; they were not alone.

Papyrus strode on purposefully, although Frisk wondered if he had any clearer an idea of where the two of them were going than they did. At one point, when they reached an intersection of hallways, he made to round a corner to another corridor when all of the lights within it went out.

“…” he said, gaping. Frisk agreed whole-heartedly. “ANOTHER WAY, THEN.”

No sooner had the words left his mouth than the lights in two of the other corridors flickered out as well, leaving only the hall ahead of them lit. Even the way they'd come had been submerged in shadow. Frisk gulped, and tightened their grip on the thing in their pocket.

“…THAT WAY? ARE YOU FINE WITH THAT, FRISK?” Papyrus asked.

Frisk nodded.

This happened several more times as they traversed the Core; lights would short out before they could enter a corridor, while doors locked and unlocked to deny or grant them passage. Sometimes, with increasing frequency as they went on, Frisk thought they saw tall, indistinct forms at the periphery of their vision. Papyrus never mentioned the apparitions, but from the way he would glance at the shadows every now and then Frisk felt sure that he saw them, too.

Eventually, the Core's tricks with lights and locks lead them to a room deep within the building Frisk had never seen before. Within it was a desk and a large number of workbenches, most of which had been shoved against the walls, leaving the wide center space mostly empty. Papers and half-finished devices had been left strewn about, as if its inhabitant had left in the middle of something with the intention of returning. As soon as Frisk and Papyrus entered the room, the door swung shut and locked; Frisk thought they saw shadowy shapes pressing against it as it closed.

“H-HEY! WHAT'S THE MEANING OF THIS???” Papyrus demanded, rounding on the door. “SORRY, FRISK, THIS… THIS ISN'T WHAT I HAD IN MIND.”

A knocking noise on the other side of the room drew their attention. From under one of the workbenches, a pale shape emerged, seemingly growing as it did so and dividing into the three Memoryheads. Frisk pulled out their cellphone and put it on speaker, so Papyrus could also hear whatever it was the Amalgamates had to say. They'd never made much sense before, but if there was even a chance they could explain what was going on, Frisk wanted to hear it.

“WHAT'S GOING ON? ARE YOU DOING THIS?” the skeleton asked.

“TIME HAS STABILIZED– SCATTER THE DARKNESS– BRING EVERYTHING BACK TOGETHER.” the cacophony said in deep, distorted voices.

Shadows flickered and shattered in the corners of the room, forming wavering silhouettes. Having said their piece, the Memoryheads withdrew back together, condensing into a single form. Suddenly, hundreds of shadows and other dim shapes flickering in and out of existence began to fly away from the walls, surrounding- no, merging with- the curious Amalgamates. Papyrus put a hand on Frisk's shoulder and took a step forward, so he was standing between the human and the apparitions.

Frisk dialed Alphys's number. It rang for only a brief while before the scientist picked up.

“F-frisk? W-what's up? The C-Core is h-having some issues, s-so…” their jittery friend said.

“I know, me and Papyrus are here. The Memoryheads- I'm not sure what they're doing-”

“Th-the Amalgamates?!” Alphys sounded shocked. “W-where are you?” she demanded.

“Some kind of old workshop.” Frisk said. “I think this is how we got here…”

As the human tried to give Alphys directions, the shadows continued to whirl around the Memoryheads like a dark tornado. While the first shapes to manifest had been vaguely person-shaped, now the majority of them were small and indistinct, like fragments of shattered glass. The way they drifted around before attaching themselves to larger pieces reminded Papyrus of something- the monster in the woods!

He frowned, and pulled the old photograph from his scarf. The top half of the photograph was no longer vacant; it was occupied by a skeleton who Papyrus could tell would be even taller than he, who had his arms around young Sans and Papyrus's shoulders. This newcomer stood straight up with impeccable posture, and he wore a white turtleneck shirt under a pristine, long black coat. There were hairline cracks in his skull, some trailing from above his right eye, and others beneath his left. His smile was not lazy or enthusiastic, but full of the kind of pride Papyrus normally only saw when Toriel was speaking of what Frisk had been up to lately. Who was he? And why had he suddenly appeared in a picture of Sans and Papyrus?

“FRISK, WHEN YOU CAN, CALL SANS. UH… TELL HIM THAT WE'RE IN THE CORE… AND SOME OTHER SKELETON JUST SHOWED UP IN A PHOTO OF US…” Papyrus said, showing them the photograph for reference.

More distinct shapes walked from the darkness across the room- strangers, entirely gray strangers. The first could have passed as the identical twin of another monster Papyrus knew, if only he was orange. Beside the first stood a lanky fellow, face hidden in black except for a wide rictus of a smile. Between them was a small scaly child in a striped shirt, with empty eyes and a bleak expression. Looming behind these three was an oversized and wide-eyed head, which rose up from the ground on a disembodied neck.

When Frisk saw them, they took their closed hand out of their pocket. They uncurled their fingers from around the object they had been holding- another piece of the mystery monster. It drifted away from them, joining the other fragments which were assembling in the middle of the room like some kind of jigsaw puzzle.

“FRISK? WHERE DID YOU GET ONE OF THOSE???”

It was then that the door slid open behind them, and Alphys hurried inside.

“Huff… puff… What's going on?” she asked. “You said the Memoryheads were here, but… wait, are they in _there_?!”

Frisk nodded, then started calling Sans.

The conglomeration of shadows suddenly collapsed on itself. There was no sign of the Memoryheads as Papyrus recognized them, just a single skeletal monster lying on the floor as if he'd fallen there. Unmistakably, this monster that had just assembled itself from the Memoryheads, and the new skeleton standing in the photograph, were one and the same, although now he looked like an approximation of who he once was. It was as if the goopy, changing shape Papyrus had seen back in Snowdin had been suddenly congealed or forced into a more distinct form and solidified that way.

Wide, deep cracks gaped in his cranium, like chunks of bone had been sliced out and removed. His left eye was open wide but his right was partially shut. And as for his mouth- Papyrus felt reasonably certain that he was smiling, but it was difficult to say. Unlike a proper skeleton's teeth, the newcomer's were all different widths and lengths, that were smushed together beside each other in one deformed mouth and refused to fit neatly, so that even when he tried to clench his jaw there were gaps. Yet he no longer seemed blurred or shattered, but whole, in spite of these oddities.

_Gaster_. He was Gaster, Papyrus knew with great certainty. He blinked. How had he remembered that? Although, something still didn't feel quite right about calling the new skeleton by that name.

“Uh, I _think_ Sans is on his way.” Frisk said quietly. “I sounded like he dropped his phone when I told him.”

Sure enough, in a few moments they found that Sans was standing in their midst.

“SANS!! DO YOU KNOW WHO THIS IS???” Papyrus asked.

Sans continued to stare at the new monster with utter disbelief, as if he hadn't heard what Papyrus had said. Then, moving in the trance-like manner of a sleepwalker, he went out into the middle of the room, and knelt by the strange skeleton's side.

He spoke in a stunned whisper, but in the silence that had fallen everyone heard him: “dad?”

**Notes for the Chapter:**

> And on that bombshell, it's time to get down to finishing up Chapter 6 before I post it next Sunday.
> 
> In the meantime, have a deleted scene from the very end of this chapter:  
> “WHO- WHO IS THAT???” Papyrus asked.  
> Sans continued to stare at the new monster with utter disbelief. “the builder of the CORE…" he said dramatically. "our father.”  
> “WHAT?!” Papyrus said, shocked.  
> Frisk turned to Alphys. “Is this the part where one of us faints?” they asked quietly.  
> “Oh, I am SO on it.” the lizard managed to get out before she fell back and passed out.


	6. Close Together

**Summary for the Chapter:**

> Frisk and their friends try to make sense of the bizarre situation in the deserted Core workshop (try being the operative word here).

Frisk and Alphys looked from Sans to Papyrus, and back again, the shock of seeing five total strangers appear out of nowhere overwhelmed by the revelation that one of them was someone they (well, one of them) knew.

“Dad?” Alphys said blankly. “Uh, Papyrus, do you know what's going on…?”

“'DAD'???” Papyrus repeated, in an equally confused tone. “DAD. UH. WE HAVE A DAD? HE'S OUR DAD? ARE YOU SURE, SANS?”

He looked back at the photograph. That _would_ explain why this Gaster fellow had suddenly shown up with Sans and Papyrus. And Dad did seem like a more fitting name for him, but…

“WHY DIDN'T I KNOW THAT?” Papyrus asked worriedly.

Really, his father's identity- his father's very _existence_ \- seemed like the kind of thing he should have known. He wracked his brains for something, anything from his early memories that might have something to do with this perplexing situation. A few faint flutterings of recollections, the idea that yes, indeed, he had been aware of his father at some point, came to him, but beyond that he couldn't remember a thing.

Well, if he was going to get the hang of this whole “having a father” thing (Again?, he wondered), he wasn't going to do it standing back and watching as his jaw hit the floor. He strode across the room, and stood by Sans.

“IS HE OKAY…?” he asked. Gaster, Dad, whoever he was, seemed to be out senseless.

Sans was trembling, and after a second Papyrus realized to his amazement that he was actually crying. His brother never cried in front of other people; heck, Papyrus had a hard enough time getting him to so much as confess to being genuinely sad, let alone this affected.

“better.” Sans said shakily.

Papyrus desperately wanted to ask just what had happened to Dad that made him turn into a goopy, intangible vanishing man for so long, but that would have to wait. First, they'd have to make sure that “better” did, in fact, mean “okay”, and not just “better off than being turned into a bunch of ghosts and Memoryheads for who-knows-how-long”.

At the same time Alphys and Frisk, seeing that this third skeleton was being tended to, crossed the room to the four gray, empty-eyed newcomers. They were apparently in a daze, blinking against the lights and slowly looking about their environment as if seeing it for the first time. The child happened to meet Frisk's eyes, and their eyes became slightly less wide as they peered at the human; then, once they realized that they were indeed looking at another person, they startled and their eyes became as large as saucers.

“Wh-who are you?” Alphys asked them.

The simplest of them narrowed his eyes. “I'm… um…”

His frown deepened, and he looked down to the floor beside him, concern over this lapse in memory written all over his plain face.

“Uhh, it's okay!” Alphys said lamely. “Y-you d-don't have to t-tell me now!”

She paused for a moment. “D-do you know who h-he is?” she asked, pointing over her shoulder to the stricken skeleton in black.

“Dr. Gaster!” piped up the gray monster with a wide grin. He seemed excited by the chance to use his voice. The head nodded in confirmation, which Alphys, at least, found rather unnerving, as without a body it simply seemed to bob back and forth in front of her.

The scientist furrowed her brows. “Dr. Gaster… Oh! Dr. Gaster!” she exclaimed. “He- h-he was… Um.”

She lapsed into confused silence.

Behind her, Gaster stirred at the sound of his name. His sockets widened, and he slowly turned his head to look at the people around him. When he realized they were none other than Sans and Papyrus, he tried to speak, but whatever it was came out as garbled nonsense. He frowned, as much as he was able to.

“y-you're back!” Sans said, voice breaking. “you're actually back!”

“HI, DAD.” Papyrus added awkwardly, for once uncertain of what to say.

Gaster relaxed, and then struggled a bit trying to move his arms, like he hadn't quite figured out how they worked.

“DO YOU WANT TO GET UP?” Papyrus asked. He imagined lying on the floor like that wasn't terribly comfortable.

Alphys startled. “Uhh, I'll get a chair! W-wait a moment!” she said, then hurried off to one of the many workbenches as Papyrus helped his father up into a sitting position. He needed more help from his sons to stay upright, to his clear dismay.

“WHAT HAPPENED TO YOU??” Papyrus asked him. He knew his father probably wouldn't be able to explain, but it felt more polite to at least try to ask him first.

But again, answers had to wait for later, as it quickly became apparent that they had to do more for the five people who had suddenly decided to start existing again in the forgotten workshop than gawk and pull up a chair or two. After a brief discussion they decided, rather wisely, to pass the buck, call up Toriel, and ask her to come to the Core (so that she could decide how to sort out the situation), and also if she happened to know where they might find a wheelchair.

 

The scene Toriel arrived in when she found her way to the old workshop, pushing a makeshift wheelchair before her, was baffling to say the least.

A fair amount of monsters were sitting in chairs arranged more or less in a circle in the center of the disorderly room. Papyrus was wearing an uncharacteristically anxious expression, and he was seated next to a skeleton Toriel would have sworn she'd never seen before, but seemed awfully familiar, somehow. This stranger was clutching the arms of his chair very tightly, as if he was afraid he might fall out of it; she could see why they had asked about the wheelchair. Sans, on the other side of the new skeleton, was crying openly. Three gray monsters, two adults and one morose child, were sitting silently on the other side of Sans, staring at the floor as if it were the most interesting thing in the world. Frisk was fidgeting in their seat, probably because of the large head monster that was… standing? looming? beside them. Alphys was fretting- well, that wasn't baffling.

“What has happened here?” Toriel asked.

The people she knew glanced at each other, as if trying to telepathically come up with an explanation together. This was clearly going to be one of _those_ stories.

“Uhh. Maybe we should start w-with introductions???” Alphys suggested, poking her fingers together nervously. The gray people looked away, at the floor, ceiling, walls, as if hoping no one would ask them to explain themselves.

Papyrus looked over at his brother, who was still crying, then cleared his throat (how, Toriel did not know).

“THIS IS DR. GASTER.” he said of the new skeleton. “HE'S OUR DAD.”

Toriel raised an eyebrow. “Is he all right? What happened to you, Dr. Gaster?”

For explanation, she looked to Dr. Gaster; Papyrus and Alphys looked to Sans; Frisk looked to the gray people.

Finally, Sans spoke.

“he used to be the royal scientist.” he began. Alphys's eyes widened with recognition. “he built this place. but…”

Sans's voice broke on the last word, and he had to stop talking for a moment. Then, ever so slowly, Dr. Gaster let go of his chair, and with a heavily shaking arm managed to put his hand over his son's. The shorter skeleton took a deep, shuddering breath, and went on.

“h-he fell in…” he said quietly. “it… he was scattered… and erased from t-time entirely.”

Papyrus's jaw dropped so far Toriel thought it would fall off, and he gripped the arms of his own chair tightly. Alphys gasped in shock, holding her hands in front of her face. “Ohmygosh!!!” she said, horrified. Toriel's eyebrows flew up in surprise, and though she longed to ask for clarification, for an explanation of how, exactly, that was possible, and why she hadn't been informed of anything like this before, she too saw that it would be better to get these strangely unfamiliar monsters somewhere more comfortable before she pestered them with difficult questions.

Frisk, strangely enough, didn't look surprised at all by Sans's words, simply sympathetic.

 

“WHERE _WERE_ YOU?!” was Undyne's first reaction to seeing them all coming down the road toward the house they had meant to stay the night in. The fish monster was standing on the front porch, arms crossed, mouth turned down in an angry, all-too-toothy frown.

“WHY WASN'T I INVITED?!” was the second reaction, followed closely by a meek “…Um. Who are they???”

She seemed the most shocked to see the small gray child, out of all of the newcomers. Undyne narrowed her eyes when she caught sight of her, mouth half-open as she tried to figure out what to say.

“Hey…” she managed at last; it was a start, at least. “Aren't you Kid's sister?”

The child cocked her head, and though her empty expression still showed very little emotion, she seemed a bit surprised, as if she hadn't heard the name in a long time.

“Kid?” The child blinked in recognition. “I… I am!”

Undyne's eyes widened in amazement. “Oh my gosh!!! Your family-” Her face scrunched up; her enthusiasm was outpacing her memory a little. “Your family was looking for you, Mina!” she said. “Uh, your name _is_ Mina, right?”

“probably.” Sans cut in, clearly eager to get things settled. “let's just get inside for now.”

For his part, Gaster didn't seem to mind the delay. He may have been amongst people who considered him a stranger, and still weak from his ordeal, but as he sat there, whole for the first time in eternity, it was clear for anyone to see that he was content.

**Notes for the Chapter:**

> I went with "Mina" for Monster Kid's sister's name because there weren't any other words for child that could double as a name, but Mina at least sounded kinda like "minor".
> 
> Chapter 7, which is probably going to be the last, will probably not be posted tomorrow on Sunday, unfortunately. Hopefully it will be up on Monday, Tuesday at the latest I can foresee right now. Sorry.


	7. Close Knit

**Summary for the Chapter:**

> Although everyone's back to their proper place in space and time again, there's still a lot of recovering to be done, and questions to be answered.

**Notes for the Chapter:**

> Originally, Chapter 7 had three parts that would comprise the epilogue. I got writer's block for part three, which is why I had to delay this posting, but I found today that the first two parts were long enough to be a chapter (albeit a short-ish one) by themselves, so I figured I'd split it up and make this an eight-chapter fic instead.

While Undyne remained with Alphys in the Underground, so the scientist could continue to complete her work, the others all headed up to the surface as soon as possible. They first headed to Toriel's house, to drop off Frisk and the gray monsters (seeing as they still didn't know who all of the gray monsters were, let alone who their families were, Toriel's house seemed like the best accommodations for them). Then, Toriel accompanied the skeletons back to their home to assist them with whatever they needed.

Eventually, once Gaster was at least mostly settled, Toriel had to leave again and make sure her gray guests hadn't already had their day ruined by the world's vilest houseplant. Gaster was exhausted from his ordeal, and was resting in Papyrus's bed (Sans's bed, while in better condition than the one he'd had Underground, was still not up to actually having anyone sleep in it). Sans and Papyrus were sitting nearby. With only his brother around, Papyrus figured it was finally a good time to ask his questions.

“SANS, WHY DIDN'T I REMEMBER HIM?” he said plaintively. In truth, there was still a lot about their father that to Papyrus was vague and nebulous, but it was clearing up bit by bit as time went on.

“it wasn't your fault, bro.” Sans began, staring ahead. “when he fell into the core, he wasn't killed, he was… removed. from time, i mean. it was like he never existed. so no one remembered him, because technically, there was nothing to remember in the first place.”

Papyrus looked down. “BUT IF HE STOPPED EXISTING, WHY IS THE CORE STILL HERE? …WHY WERE _WE_ STILL HERE???”

Sans shrugged. “i dunno. don't really have any data to analyze, at least right now.”

Papyrus's sockets widened a little. Data? Was Sans going to go back to doing science-y stuff? It would be wonderful if his brother started showing more than a passing interest in things again. Sans'd been down for so long, and Papyrus had been really worried about him, especially since he didn't even seem much better when they reached the Surface. He'd never figured out why his brother was so… dispirited. His brother never told anybody anything, just covered up whatever he was going through with a constant grin and an often-forced laugh, and Papyrus was afraid to push the matter.

The taller skeleton's own spirits brightened. First their father returned to them, and soon, maybe, Sans _might_ start being genuinely happy again! All things considered, their future was looking pretty bright.

“WELL, AT LEAST HE'S BACK!!! THAT'S ENOUGH FOR ME RIGHT NOW.” he remarked cheerfully.

“heh, you said it.” Sans said, inhaling and exhaling sharply.

Papyrus frowned. There was that forced laugh again; sure, it sounded pretty similar to Sans's actual laugh, but they weren't brothers for nothing. Something about the situation was still bringing Sans down, and Papyrus was fairly confident that if it only had to do with their father's recovery, Sans would've said so. No, his brother was trying to cover something up again.

But what? Papyrus pondered the matter for a moment. Did he, too, feel bad about forgetting their father?

His sockets widened in horror as the pieces of the puzzle fell into place. Sans knew an _awful_ lot about their father's predicament, but as he'd just said, he hadn't looked at any data or anything about it yet. If his memory had worked like Papyrus's or Alphys's, he wouldn't have even known that Gaster was their dad at first, let alone how he disappeared or the state he'd been ever since.

“SANS…” Papyrus said quietly.

“yeah, papyrus?”

“WHY DID YOU REMEMBER HIM?” he asked tentatively.

Sans's sockets widened and his grin tightened by an almost imperceptible amount. “what?” he asked, in his typical lazy tone.

“YOU _DID_ REMEMBER HIM.” Papyrus said, aghast. No wonder his brother was depressed! “WERE- WERE YOU THE ONLY ONE? THIS _WHOLE TIME_? SANS, OH MY GOSH…!!!”

Before Sans could get in another word edgewise, the taller skeleton reached over and glomped him. Sans didn't say anything for a moment. He shuddered, and Papyrus realized he was crying again. Papyrus had a few tears caught in his eyes himself.

“yeah… heh… y-you got me there…” Sans managed at last.

“I'M SORRY THAT YOU H-HAD TO GO THROUGH THAT.” Papyrus said. “BUT, THINGS WILL BE BETTER NOW! I PROMISE!!!”

“th-thanks…” Sans mumbled.

Their family was back together, he'd finally gotten Sans to admit something was bothering him, and hopefully that wouldn't bother him for much longer; yes, from Papyrus's point of view, things were looking up.

 

 

“H-hey, Dr. Gaster,” Alphys asked. “H-how did you, uh, b-become the Memoryheads?'

The next two months had been fairly hectic. Reuniting the gray monsters- who in spite of their return showed no sign of regaining their former colors- with their relatives was one of the major difficulties. In many cases, their friends' and families' memories took days, weeks, to come back even partially, forcing the gray monsters to stay with Toriel in the meantime. When their families finally did recall their lost loved ones, they were naturally horrified by what had happened, and wanted an explanation of what had happened.

And an explanation had been slow in coming, after the strange events in the Core. Sans, who had always been quite reticent, seemed not to know as much about what had happened to the gray monsters as he did what had happened to Dr. Gaster. He was able to help figure out who they were, but otherwise kept fairly quiet about it all. Besides that, he and Papyrus, whose own memories were returning swiftly, were quite busy trying to help their father through his recovery, so no one pressed the matter. And what a recovery it was, after spending so long alone and scattered in mostly-incorporeal pieces across the void, with hardly any contact with anyone else. Speech and movement were naturally difficult for Gaster, what with him having to readjust to existing at a single point in space and time, especially with his body not being what it once was.

As time went on he had made some progress, and after those two months had passed he was able to speak, albeit slowly, and walk a little under his own power with the help of a cane. As soon as he felt up to it, Toriel had invited all three of the skeletons and their other friends to her home for dinner to celebrate, and it was here that Alphys popped her question. Toriel- with Undyne and Papyrus's help- was getting dinner ready, Sans was helping Toriel run damage control, while Alphys, Frisk, and Gaster were sitting at a table in the main room of the house.

“I… hmm.” Gaster paused to think for a moment. When he came up with a full answer, he spoke slowly. “I don't remember all that well. For the most part, I existed… outside of space and time; it was hard for me to interact with anything, because I was in so many places at once.” he explained.

“But, I think at least once, when you were starting your experiments, a part of me was able to exist tangibly somewhere. I was found, and whoever found me thought I had fallen down, and took me to you. Somehow, I must have stayed where I was long enough to be injected with determination.”

Alphys nodded thoughtfully. “Hmm… and I didn't recognize you because my memories were gone… but how did you become all three of the Memoryheads, then?” she asked.

Gaster did an approximation of a shrug. “Maybe I was found and mistaken for a fallen monster three times. I think those parts of me were determined enough to exist linearly. Then, other fragments of me were able to join in, and the determination melded me together, somewhat. There always was more of me around the Core and the Labs.”

Alphys frowned. “Why couldn't you reform back then, in that case?”

Frisk took a sudden interest in the carpet, swinging their feet back and forth. Their feet brushed the floor, making a shuffling noise.

“For a long time, there was an… anomaly, you might say, in the space-time continuum.” Gaster began cautiously. Frisk swung their legs faster, and the shuffling got louder. They were still looking resolutely at the floor.

Alphys's eyes widened. “An anomaly?! Oh my gosh, what was it? A-are we safe?” she fretted.

“It's gone, now.” Gaster said as swiftly as he could, not looking at Frisk. “It destabilized time, and made it difficult for me to exist in one place at a time, or even figure out where I was. But it seems to have resolved itself. No need to worry over it now.”

The reptilian scientist didn't look entirely convinced, but she nodded and didn't ask any more questions about it.

“As soon as time was stable enough for me to be able to bring myself together, I used the determination of my amalgamated forms to anchor myself to that point in space, and pulled myself back together again.” he finished.

The conversation wound down on that topic after that, and eventually Alphys moved it on to what she was starting to remember of Gaster. They talked for quite some time, but Frisk didn't say much more that night, to anyone, even when the subject changed again to something they were more familiar with.

**Notes for the Chapter:**

> Well, at least Papyrus finally got Sans to open up a little bit. I don't know whether or not Sans will explain the rest of the causes for his depression to anyone, but it's a start.  
> Gaster is well aware of the nature of Chara and the anomaly, but skirts around it because it'd be difficult (and probably somewhat painful) to explain, and because he knows Frisk was another one if its victims and he doesn't want to make things even more awkward for them.  
> Hope this doesn't seem too exposition-heavy. It just seems to me that now that the action's happened there's still a lot of fallout to deal with, which may be less spooky or flashy but no less necessary to tell this story in full.  
> Chapter 8 WILL be up next Sunday.


	8. Close Kin

**Summary for the Chapter:**

> Sans and Gaster have a conversation long overdue.

The night was still young when the get together cleared up, mostly because Toriel was insistent on Frisk going to bed at a normal hour. Alphys and Undyne headed away together, while Papyrus drove his brother and father back to their own home.

Incidentally, the taller skeleton went to bed at a decent time himself- it had been a while since he'd gotten some sleep, and whenever he did get it, he always made sure to go to bed early so he could wake up just as early in the morning. Sans and their father made a show of getting ready to sleep themselves but, half an hour later, Papyrus was snoring loudly (somehow) in his own room, while they were still sitting up on the sofa.

“so…” Sans said after a bit. “the 'anomaly' caused problems for you, too?”

Gaster nodded. “At first, my main problem was trying to figure out what had happened to me, what I could do, how to just… deal with everything. Eventually I began to conceive of a way I might reform. By then that flower, Frisk, and the… anomaly went about starting and stopping a lot of derivative timelines. That just scattered my fragments and consciousness even more. And though I never had the misfortune of encountering the anomaly in person, seeing what it did to you…”

He shuddered, and looked down, closing his eyes. They sat in silence for a moment.

“I'm sorry that you had to be aware of it all…” Gaster said faintly.

Sans felt a sinking feeling where his stomach would be, if he had one.

“heh… thanks.” he said with indifference, although he could not entirely get rid of the tension behind it. “not like it's your fault, though.” he added.

Gaster sucked in a breath. “But it is.” he said sorrowfully.

A deep chill seeped into Sans's marrow. His grin tightened.

“Your ability to retain memories across timelines, however faintly… I am to blame for that.” His father exhaled sharply, and a pained look crossed his face. “That, and so much more.”

A silence fell as Gaster tried to keep himself together, and gather his thoughts. The cold seemed to deepen as the quiet continued.

“i'd suspected.” Sans admitted, looking straight ahead. His sockets were dark. Gaster lowered his head. “i couldn't think of any other explanation for it. and my magic?”

“Enhanced, yes.” Gaster confessed weakly. “I was worried about you, Sans. When you were young, I tried to find a way to bolster your health and resilience. But the only way to do that that I could find, could have weakened them even further. So instead, I tried to give you another way to defend yourself, by letting you create far more bullets than almost any other monster. The results… were far better than I expected.”

They lapsed once more into gloomy silence.

Finally, Sans broke it. “but… what about retribution? and my long-range stuff? and what does that have to do with my memory?”

Gaster seemed to shrink into himself.

“After the deaths of the King and Queen's children, I devoted a large part of my research to finding ways to… kill humans.” he explained. “It was only a matter of time before one fell down, and it seemed to me more likely that an adult would fall than a child, and those are powerful enough. They could pose a serious threat to the Underground if not dealt with quickly. So I went back to experimenting with ways to enhance a monster's strength. Damage dealt over time… powerful bullets that could manifest at a distance… seemed like good ways to handle humans.

“You had already assimilated the previous boosts with no ill effects. You were the ideal person to try… to give these new abilities to. Besides, I told myself, it would make it easier for you to defend yourself.” he said.

He held his head in his hollowed hands. Neither skeleton could look at the other.

“I never wanted you to be a weapon, Sans. I promise.” Gaster went on. “And thankfully you were still young when the next few humans fell. But when they did, and I began studying determination…”

“…you learned about saving. and loading.” Sans said in a hollow voice. He'd always been pretty clever for his age, and just old enough to start helping his father with his experiments at that point. “you figured it was probable that eventually, a human would fall that would be determined enough to reset time.”

Gaster took a deep breath, and nodded. “Exactly. And then we built the machine, and it began reporting anomalous activity in space-time… I knew it wasn't just a possibility. I thought, wouldn't it be better, make things easier, if we could turn the tables on the human? If we could be just as aware of its meddling in time as it was? That, I thought, might buy us the time, so to speak, to find a way to defeat it for good.”

He let out a mirthless laugh. “You'd already handled several… experiments, even the teleportation, and you were assisting me with the project, s-so… I…”

A few tears formed at the edge of his left socket, running down the edges of the crack in his skull. He held his head in his hand.

“I'm sorry.” he said after a moment. “It was wrong. All of it.”

Sans shifted uncomfortably in his seat. “well, you were in a difficult position, by the sound of it-” he began.

“That doesn't excuse _any_ of it!” Gaster exploded. “What kind of scientist am I? What kind of father am I?! I performed experiments in secret on my own son, I never gave you a choice in the matter- but then, you were just a child, what would it have mattered if I did? I never even let you know what was happening… and I kept doing it. And when you started helping me with my projects I still didn't tell you, because I was too cowardly to own up to my _idiotic_ mistakes.”

Gaster balled his hollowed hands into fists. “I'm sorry.” he said, as much for the outburst as for anything else.

“I was _going_ to tell you.” he said in a strained voice. “At least, I told myself I was going to tell you. After how long I kept it a secret, I don't know if I ever would have.”

Anger returned to his voice. “And then I went and destroyed myself. I left you and Papyrus behind. I left you alone, with responsibilities and abilities you weren't prepared to handle, and then,” His voice cracked; more tears dripped from his left socket. “the anomaly came…”

“if you were too… afraid to tell me before,” Sans said slowly. “why tell me now?”

Gaster did an approximation of a shrug.

“Your priorities change, when you have an eternity of emptiness to think about what you've done.” he said. “Look… I know this is a lot to handle… too much, probably. And I'm fairly recovered, by now. If you don't want me around, after all this, I understand compl-”

“ _no_.” Sans snapped, startling his father, who stared at him with what seemed to be bewilderment.

“to be honest, i don't really care about that too much.” Sans explained with a half-shrug. “i mean, yeah, that's pretty messed up… but it did come in handy… and after everything that's happened, i'm just glad to have you back.”

“ _Sans…_ ” Gaster said, his voice ragged. “All that considered, I was a pretty terrible father.”

The shorter skeleton shrugged again. “welp, like papyrus says, anyone can be a good person, if they try. you obviously regret it, and it's not like you're going to do it again.”

“Never.” his father said fiercely.

“exactly.” Sans said. “i forgive ya.”

**Notes for the Chapter:**

> Thank you so much to everyone who's been keeping up with this! I hope this last chapter is satisfying.
> 
> The long-range thing was meant to refer to the bones that Sans can send through the menu- I imagine that normally, monster summon their bullets near to them, and send them out to attack their enemies, while these bones are summoned right in front of Chara, making them harder to dodge and extra dangerous.


End file.
